[GreenKeys] Loop Supply Circuit and Parts List - AND MORE

[COURYHOUSE at aol.com]

yes  please send  !
sounds  good!
Ed#
 
 
In a message dated 8/4/2012 10:00:35 A.M. US Mountain Standard Time,  
wa2hwj at att.net writes:

 
ZCZC 
I have put  together a simple 130VDC/60 ma. Loop Supply diagram 
and  materials list using FOUR readily-available parts. 
The parts  can all be acquired from Mouser Electronics and 
should not  cost more than $25. The parts can be purchased on-line 
and Mouser  usually delivers within a few days. I did not include switches, 
 fuse 
holders,  indicator lamps, a meter, jacks and an enclosure in the parts  
list. 
Those  things are a personal choice and are left up to the 
builder.  The parts listed are rated for continuous use. 
Construction is simple enough that a  circuit board would be 
overkill.  The few parts can be assembled on a perf board or 
terminal  strip. The adjustable power resistor uses a slider to  set 
the  current. A knob-type variable potentiometer rated for 25W or  better 
would have  cost a small fortune. However, many of you might 
have those  kinds of pots in the your TTY junk box. Since this 
is a  set-and-forget adjustment, the cost of the variable pot 
makes no  sense. If you are not worried about a few milliamperes 
here or  there, a fixed resistor could be used at reduced cost. 
I can send  the drawing to anyone who is interested. 
I have also  fine-tuned the “TTY Motor Control” and  
“RS232-to-Loop-Converter” circuits  and am now working on 
PC boards  for them. More about these later.... 
73, 
Jack  K0TTY 
NNNN 



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